A372290 Numbers that occur in the odd bisection of A371094.

21, 45, 69, 93, 117, 141, 165, 189, 213, 237, 261, 285, 309, 333, 341, 357, 381, 405, 429, 453, 477, 501, 525, 549, 573, 597, 621, 645, 669, 693, 717, 725, 741, 765, 789, 813, 837, 861, 885, 909, 933, 957, 981, 1005, 1029, 1053, 1077, 1101, 1109, 1125, 1149, 1173, 1197, 1221, 1245, 1269, 1293, 1317, 1341, 1365, 1389

Offset: 1

Author

Antti Karttunen, Apr 26 2024

Keywords

• nonn

Comments

Numbers that occur in array A371100.

Examples

			21 is present because A371094(1) = A371094(3) = 21.
45 is present because A371094(7) = 45.
87381 is present because A371094(85) = A371094(213) = A371094(7281) = A371094(14563) = 87381.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..62122

Crossrefs

Union of A372291 and A372292.

Cf. A102603 (subsequence), A371094, A371100.

Programs

PARI

A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); };
isA372290(n) = if(!(n%2),0,forstep(k=1,n,2,if(A371094(k)==n,return(1))); (0));

PARI

A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); };
A372290list(up_to_n) = { my(v=vector((1+up_to_n)/2), x, lista=List([])); forstep(k=1,up_to_n,2,x=A371094(k); if(x <= up_to_n, v[(x+1)/2]++)); for(i=1,(1+up_to_n)/2,if(v[i]>0, listput(lista,i+i-1))); Vec(lista); };